The present invention relates to a refrigerant compressor for use in refrigerating/air-conditioning equipment.
FIG. 7 is a longitudinal sectional view showing the construction of a conventional scroll compressor disclosed in JP-A-2000-161254.
In FIG. 7, numeral 1 designates a fixed scroll having its outer circumferential portion fastened to a guide frame 15 by means of bolts (not shown). Plate-like scroll teeth 1b are formed on one surface (lower side in FIG. 7) of a base plate portion 1a. In addition, two Oldham""s guide grooves 1c are formed substantially in a straight line in the outer circumferential portion. A claw 9c of an Oldham""s ring 9 is reciprocally slidably engaged with each of the Oldham""s guide grooves 1c. Further, from a side surface of the fixed scroll 1, a suction pipe 10a is press fitted through a closed vessel 10.
Numeral 2 designates an oscillating scroll, and plate-like scroll teeth 2b having substantially the same shape as the plate-like scroll teeth 1b of the fixed scroll 1 are provided on the upper surface of a base plate portion 2a. Thus, a compression chamber 1d is formed geometrically. A hollow cylindrical boss portion 2f is formed in the center portion of that surface of the base plate portion 2a which is opposite to the plate-like scroll teeth 2b. An oscillating bearing 2c is formed on the inner surface of the boss portion 2f. In addition, a thrust surface 2d which can slide in pressure contact with a thrust bearing 3a of a compliant frame 3, is formed on the same side surface as the boss portion 2f but on an outer side than the boss portion 2f. In the outer circumferential portion of the oscillating scroll base plate portion 2a, two Oldham""s guide grooves 2e are formed substantially in a straight line to have a phase difference of 90 degrees with respect to the Oldham""s guide grooves 1c of the fixed scroll 1. A claw 9a of the Oldham""s ring 9 is reciprocally slidably engaged with each of the Oldham""s guide grooves 2e. An extraction hole 2j is also provided in the base plate portion 2a so as to extend from the compression chamber 1d through the thrust surface 2d. An aperture portion 2k of the extraction hole 2j on the side of the thrust surface 2d is located so that the circular locus of the aperture portion 2k always stays inside the thrust bearing surface 3a of the compliant frame 3.
The compliant frame 3 has two upper and lower cylindrical surfaces 3d and 3e in its outer circumferential portion. The cylindrical surfaces 3d and 3e are supported in the radial direction of the scroll compressor by cylindrical surfaces 15a and 15b provided in the inner circumferential portion of the guide frame 15, respectively. A main bearing 3c and an auxiliary main bearing 3h for supporting a main shaft 4 in the radial direction of the scroll compressor are formed in the center portions of the compliant frame 3. The main shaft 4 is driven to rotate by a motor 7. In addition, between the outside of the compliant frame 3 and the inside of the guide frame 15, a frame space 15f is defined by sealing materials 16a and 16b disposed on cylindrical surfaces 15c and 15d, respectively. The frame space 15f communicates with the compression chamber 1d through a communication passageway 3s and the extraction hole 2i which are interconnected via the surface of the thrust bearing 3a. Thus, the frame space 15f is filled with refrigerant gas which is supplied from the compression chamber 1d and which is on the way of compression.
A regulating valve receiving space 3p is also formed in the compliant frame 3. One end (lower end in FIG. 7) of the regulating valve receiving space 3p communicates with a boss portion outside space 2h. The boss portion outside space 2h is constituted by the inner circumference of the compliant frame 3 and the thrust surface 2d of the oscillating scroll 2. On the other hand, the other end (upper end in FIG. 7) of the regulating valve receiving space 3p is made open to a suction pressure atmosphere space 1g. An intermediate pressure regulating valve 3i is reciprocally movably received in the lower portion of the regulating valve receiving space 3p. On the other hand, received in the upper portion of the regulating valve receiving space 3p is an intermediate pressure regulating spring retainer 3t fixedly attached to the compliant frame 3. Between the intermediate pressure regulating valve 3i and the intermediate pressure regulating spring retainer 3t, an intermediate pressure regulating spring 3m is received in such a manner that the spring 3m is made shorter than its natural length.
An outer circumferential surface 15g of the guide frame 15 is fixedly attached to the closed vessel 10 by shrink-fitting, welding, or the like. However, a channel is ensured by a notch portion 15h provided in the outer circumferential portion of the guide frame 15. Thus, high pressure refrigerant gas discharged from a discharge port 1f of the fixed scroll 1 is directed through the channel to a discharge pipe 10b provided on the motor side.
Numeral 4 designates a main shaft and an oscillating shaft 4b is formed in the upper end portion of the main shaft 4. The oscillating shaft 4b is rotatably engaged with the oscillating bearing 2c of the oscillating scroll 2. A main shaft balancer 4e is shrink-fitted in the lower portion of the oscillating shaft 4b. Further, under the main shaft balancer 4e, a main shaft portion 4c is formed so as to be rotatably engaged with the main bearing 3c and the auxiliary main bearing 3h of the compliant frame 3. In addition, an auxiliary shaft portion 4d is formed in the lower portion of the main shaft 4 so as to be rotatably engaged with an auxiliary bearing 6a of a sub-frame 6. A rotor 8 is shrink-fitted between the auxiliary shaft portion 4d and the main shaft portion 4c. 
An upper balancer 8a is fixed to the upper end surface of the rotor 8 and a lower balancer 8b is fixed to the lower end surface of the rotor 8. Static balance and dynamic balance are ensured by the total of three balancers including the upper and lower balancers 8a and 8b in addition to the above-mentioned main shaft balancer 4e. Further, an oil pipe 4f is force fitted into the lower end of the main shaft 4. Thus, refrigerating machine oil 10e retained in the bottom portion of the closed vessel 10 is sucked up through the oil pipe 4f. 
A glass terminal board 10f is provided at the side surface of the closed vessel 10. The motor 7 is connected with the glass terminal board 10f through lead wires.
Next, description will be made about the basic operation of the conventional scroll compressor.
A sucked refrigerant of low pressure enters the compression chamber 1d through the suction pipe 10a. The compression chamber id is defined by the plate-like scroll teeth of the fixed scroll 1 and the plate-like scroll teeth of the oscillating scroll 2. The oscillating scroll 2 driven by the motor 7 makes an eccentric turning motion while reducing the volume of the compression chamber 1d. On this compression stroke, the sucked refrigerant becomes high in pressure. Thus, the sucked refrigerant is discharged into the closed vessel 10 through the discharge port if of the fixed scroll 1.
On the other hand, the refrigerant gas of intermediate pressure on the way of compression on the above-mentioned compression stroke is directed from the extraction hole 2j of the oscillating scroll 2 to the frame space 15f through the communication passageway 3s of the compliant frame 3, so that the intermediate pressure atmosphere in this space is maintained.
The discharged gas of the high pressure fills the closed vessel 10 with the high pressure atmosphere. The discharged gas is eventually released from the discharge pipe 10b to the outside of the compressor.
The refrigerating machine oil 10e in the bottom portion of the closed vessel 10 is directed, by a differential pressure, to the oscillating bearing 2c through a hollow space 4g extending through the main shaft 4 in the axial direction and to the main bearing 3c through a side hole provided in the main shaft 4. The refrigerating machine oil 10e (which is generally formed into a two-phase flow of gas refrigerant and refrigerating machine oil because of the foaming of the refrigerant dissolved in the refrigerating machine oil) is made to have an intermediate pressure by the throttling action of the two bearings. The refrigerating machine oil 10e reaches the boss portion outside space 2h surrounded by the oscillating scroll 2 and the compliant frame 3. Then, the refrigerating machine oil 10e overcomes the force loaded by the intermediate pressure regulating spring 3m disposed in the regulating valve receiving space 3p. Thus, the refrigerating machine oil 10e pushes the intermediate pressure regulating valve 3i. Accordingly, the refrigerating machine oil 10e is introduced into the suction pressure atmosphere space 1g and sucked into the compression chamber 1d together with the low pressure refrigerant gas.
As described above, the intermediate pressure Pm1 (MPa) of the boss portion outside space 2h is substantially defined on the basis of the spring force of the intermediate pressure regulating spring 3m and the intermediate pressure exposure area of the intermediate pressure regulating valve 3i. Thus, the intermediate pressure Pm1 is controlled by a predetermined value xcex1 as follows:
Pm1=Ps+xcex1xe2x80x83xe2x80x83(1) 
wherein Ps represents the suction pressure or low pressure (MPa).
Here, the difference between the closed vessel pressure Pd (MPa) (i.e. the discharge pressure) and the boss portion outside space pressure Pm1 is an oil feed differential pressure xcex94P required for feeding the refrigerating machine oil 10e to the main bearing 3c and the oscillating bearing 2g. It is necessary to always ensure a positive value for the oil feed differential pressure xcex94P.
xcex94P=Pdxe2x88x92Pm1 greater than 0xe2x80x83xe2x80x83(2) 
On the compression stroke, the refrigerating machine oil 10e is released from the discharge port 1f into the closed vessel 10 together with the high pressure refrigerant gas. Here, the refrigerating machine oil 10e is separated from the refrigerant gas, and returned to the bottom portion of the closed vessel again.
The compression chamber 1d for the refrigerant gas always or intermittently communicates with the frame space 15f through the extraction hole 2j provided in the base plate portion 2a of the oscillating scroll 2 and the communication passageway 3s provided in the compliant frame 3. Since the frame space 15f is a space closed by the two sealing materials 16a and 16b, the pressure in the frame space 15f breathes and changes in response to the change in pressure of the compression chamber 1d. The pressure in the frame space 15f is roughly equal to the integrated average value of the pressure changes in the compression chamber 1d with which the extraction hole 2j communicates.
As described above, the intermediate pressure Pm2 (MPa) of the frame space 15f is controlled by a predetermined magnification value xcex2 determined by the position of the compression chamber 1d with which the extraction hole 2j communicates, as follows.
Pm2=Psxc3x97xcex2xe2x80x83xe2x80x83(3) 
wherein Ps represents the suction pressure or low pressure (MPa).
Here, Fpm1 represents the force tending to cause the compliant frame 3 and the oscillating scroll 2 to separate from each other due to the intermediate pressure Pm1 in the boss portion outside space 2h. In addition, Fgth represents the thrust gas force tending to cause the fixed scroll 1 and the oscillating scroll 2 to separate from each other in the axis direction due to the compression operation. Thus, the sum of the two forces Fpm1 and Fgth acts on the compliant frame 3 as a force for moving the compliant frame 3 in the opposite direction to the compression chamber 1d. 
On the other hand, Fpm2 represents the force tending to cause the compliant frame 3 and the guide frame 15 to separate from each other due to the intermediate pressure Pm2 of the frame space 15f to which the refrigerant gas on the way of compression has been directed. In addition, Fpd2 represents the differential pressure which acts on the lower portion exposed to the high pressure atmosphere. Thus, the sum of the two forces Fpm2 and Fpd2 acts on the compliant frame 3 as a force to move the compliant frame 3 toward the compression chamber.
During the steady-state operation, the force to move the compliant frame 3 toward the compression chamber is set to exceed the force to move the compliant frame 3 in the opposite direction to the compression chamber. Thus, the compliant frame 3 is guided by the engaging upper and lower cylindrical surfaces 3d and 3e so as to move toward the compression chamber. The oscillating scroll 2 moves in the same direction as the compliant frame 3 while sliding on the compliant frame 3 in close contact therewith and also causing its plate-like scroll teeth 2b to slide in contact with the fixed scroll 1.
On the other hand, the above-mentioned thrust gas force Fgth increases during the starting, fluid compression, or the like. Thus, the oscillating scroll 2 strongly presses down the compliant frame 3 through the thrust bearing 3a. As a result, there is produced a comparatively large clearance between the tooth tips and the tooth bottoms of the oscillating scroll 2 and the fixed scroll 1. Thus, the pressure in the compression chamber is prevented from abnormally increasing. This action is called xe2x80x9crelief actionxe2x80x9d, and the amount of the produced clearance is called xe2x80x9crelief amountxe2x80x9d.
The relief amount is controlled by a distance of travel by which the compliant frame 3 and the guide frame 15 collide with each other.
A part or the whole of upsetting moment generated in the oscillating scroll 2 is transmitted to the compliant frame 3 through the thrust bearing 3a. However, a bearing load applied by the main bearing 3c, and a resultant of two reactions thereof, that is, a couple produced by a resultant of counterforces applied by the two upper and lower cylindrical engaging surfaces 3d and 3e of the compliant frame 3 and the guide frame 15 act on the compliant frame 3 so as to cancel the above-mentioned upsetting moment. Thus, excellent steady-state operation follow-up action and relief action stability are ensured.
Next, detailed description will be made about the relationship of axial forces acting on the conventional scroll compressor.
FIG. 8 illustrates the relationship of axial forces acting on the oscillating scroll 2 and the compliant frame 3 in the conventional scroll compressor.
Fgth represents the counterforce generated by compressing the refrigerant gas, and Ftip represents the tooth tip contact force generated by making the fixed scroll 1 and the oscillating scroll 2 slide in contact with each other at the tooth tips. Thus, the counterforce Fgth and the tooth tip contact force Ftip act on the oscillating scroll 2 in the downward direction in FIG. 8. On the other hand, Fpm1 represents the force tending to cause the oscillating scroll 2 and the compliant frame 3 to separate from each other by the pressure Pm1 in the boss portion outside space 2h. In addition, Fpd1 represents the force acting on the inside of the boss portion of the oscillating scroll exposed to the high pressure atmosphere due to the differential pressure. Further, Fth represents the thrust contact force generated by the thrust surface sliding in contact with the compliant frame 3. Thus, the forces Fpm1, Fpd1 and Fth act on the oscillating scroll 2 as upward forces in FIG. 8. Here:
Fpm1=Spm1xc3x97(Pm1xe2x88x92Ps)xe2x80x83xe2x80x83(4) 
Fpd1=Spd1xc3x97(Pdxe2x88x92Ps)xe2x80x83xe2x80x83(5) 
wherein:
Spm1 represents an acting area (m2) of the intermediate pressure Pm1 in the boss portion outside space
Spd1 represents an acting area (m2) of the discharge pressure Pd in the boss portion inside space
Pd represents the discharge pressure (MPa)
Ps represents the suction pressure (MPa).
Accordingly, the force acting on the oscillating scroll 2 is expressed by:
Fgth+Ftip=Fth+Fpm1+Fpd1xe2x80x83xe2x80x83(6) 
On the other hand, the force Fpm2 and the thrust contact force Fth act on the compliant frame 3 as downward forces in FIG. 8. The force Fpm2 is a force tending to cause the oscillating scroll 2 and the compliant frame 3 to separate from each other due to the intermediate pressure Pm1 of the boss portion outside space 15h. The thrust contact force Fth is generated when the compliant frame 3 slides in contact with the oscillating scroll 2. On the other hand, force Fpm2 and force Fpd2 act on the compliant frame 3 in the upward direction in FIG. 8. The force Fpm2 is a force tending to cause the compliant frame 3 and the guide frame 15 to separate from each other due to the intermediate pressure Pm2 of the frame space 15f. The force Fpd2 is generated by the differential pressure acting on the lower end portion of the compliant frame exposed to the high pressure atmosphere.
Fpm2=Spm2xc3x97(Pm2xe2x88x92Ps)xe2x80x83xe2x80x83(7) 
Fpd2=Spd2xc3x97(Pdxe2x88x92Ps)xe2x80x83xe2x80x83(8) 
wherein:
Spm2 represents an active area (m2) of the intermediate pressure Pm2 in the frame space
Spd2 represents the area (m2) in which the compliant frame is exposed to the discharge pressure atmosphere at its lower end
Pd represents the discharge pressure (MPa)
Ps represents the suction pressure (MPa).
Accordingly, the force acting on the compliant frame 3 is expressed by:
Fpm1+Fth=Fpm2+Fpd2xe2x80x83xe2x80x83(9) 
By the simultaneous equations (6) and (9), the tooth tip contact force Ftip and the thrust contact force Fth can be obtained.
Ftip=Fpd1+Fpd2+Fpm2xe2x88x92Fgthxe2x80x83xe2x80x83(10) 
Fth=Fpm2+Fpd2xe2x88x92Fpm1xe2x80x83xe2x80x83(11) 
The expression (10) shows that the tooth tip contact force Ftip increases as the force Fpm2 (the force tending to cause the compliant frame 3 and the guide frame 15 to separate from each other due to the pressure Pm2 of the frame space 15f) is set to be larger. In other words, the tooth tip contact force Ftip increases as the intermediate pressure Pm2 of the frame space 15f is set to be higher (the value xcex2 is set to be larger).
On the other hand, the expression (11) shows that the thrust contact force Fth decreases as the force Fpm1 (the force tending to cause the compliant frame 3 and the oscillating scroll 2 to separate from each other due to the pressure Pm1 of the boss portion outside space 2h) is set to be larger. In other words, the thrust contact force Fth decreases as the intermediate pressure Pm1 of the boss portion outside space 2h is set to be higher (the value xcex1 is set to be larger). That is, it is so constructed that the thrust sliding loss can be reduced so as to be useful in saving the electrical power supplied to the compressor.
As described above, the tooth tip contact force Ftip or the thrust contact force Fth can be adjusted desirably by adjusting the pressure Pm1 in the boss portion outside space or the pressure Pm2 in the frame space. However, positive values must be always ensured for the two forces in order that the compressor performs out a normal compressing operation.
Ftip greater than 0xe2x80x83xe2x80x83(12) 
Fth greater than 0xe2x80x83xe2x80x83(13) 
Referring now to FIG. 9, the sealing materials will be described hereinafter. The sealing materials are provided on the cylindrical engaging surfaces of the guide frame 15 and the compliant frame 3 so as to form the frame space 15f. 
Since the refrigerant gas on the way of compression is extracted and introduced into the frame space 15f, the pressure levels during the normal operation are generally expressed by:
Ps less than Pm2 less than Pdxe2x80x83xe2x80x83(14) 
Accordingly, the sealing materials usually constituted by a U-ring for preventing discharge pressure gas from entering the frame space 15f and another U-ring for preventing gas from leaking from the frame space 15f to the suction pressure atmosphere are provided in the direction shown in FIG. 9. Teflon or the like is often used as the material of the U-rings.
In the conventional scroll compressor, as described previously, when the intermediate pressure Pm1 of the boss portion outside space 2h is set to be high, the thrust contact force Fth shown by the expression (11), that is, the thrust sliding loss can be reduced so that the electrical power supplied to the compressor can be saved. However, if the pressure Pm1 is set to be too high, the thrust contact force Fth takes a negative value (Fth less than 0). Accordingly, the oscillating scroll 2 and the compliant frame 3 are separated from each other so that a normal compressing operation cannot be carried out. In addition, the oscillating scroll 2 fluctuates in the clearance of the axial relief amount so that the oscillating bearing functions as one-sided bearing. Thus, there is a problem that abnormal wear, damage, or the like, is caused.
Likewise, if the pressure Pm1 is set to be too large, the expression (2) xcex94P=Pdxe2x88x92Pm1 takes a negative value (xcex94P=Pdxe2x88x92Pm1 less than 0). Accordingly, the differential pressure for feeding oil to the oscillating bearing 2c and the main bearing 3c cannot be ensured, so that there is a problem that the bearings are damaged or the like.
The present invention has been made to solve such problems. It is an object of the present invention to provide a scroll compressor of the type described which has high performance and high reliability in that an upper limit is set to the value a in the expression (1) so as to preset the pressure Pm1 of the boss portion outside space 2h and keep the thrust contact force Fth proper so that the thrust sliding loss is reduced while performing a normal compressing operation without occurrence of separation between the oscillating scroll 2 and the compliant frame 3, that abnormal wear or damage is not produced in the oscillating bearing, and that the oil feed differential pressure is ensured to prevent the oscillating shaft and the main shaft from being damaged.
In the conventional scroll compressor, if the intermediate pressure Pm2 of the frame space 15f is set to be too low, no force is generated to move the compliant frame 3 toward the compression chamber. As a result, the value of the tooth tip contact force Ftip becomes negative. Thus, during the steady-state operation, the fixed scroll 1 and the oscillating scroll 2 are separated from each other so that a normal compressing operation cannot be effected. In addition, there is such a problem that the oscillating scroll 2 fluctuates in the clearance of the axial relief amount so that the bearings are damaged. On the contrary, if the intermediate pressure Pm2 is set to be too high, the tooth tip contact force Ftip becomes so large that the sliding loss increases. Thus, the electrical power supplied to the compressor increases. In addition, there is such a problem that the tooth tips are worn abnormally, and as the worst case, the tooth tips seize.
The present invention has been made in order to solve such problems, and it is another object of the present invention to provide a scroll compressor of the type described which has high performance and high reliability in that the value xcex2 in the expression (3) is set in a proper range with the result that the compliant frame 3 is moved toward the compression chamber positively so that the fixed scroll and the oscillating scroll are brought into close contact with each other by a proper pressing force in the axial direction of the compressor and thus the tooth tip contact force Ftip is maintained so proper that a normal compressing operation is ensured, that the bearings, for example, are prevented from being damaged, that the sliding loss is prevented from increasing, and that the tooth tips are prevented from being abnormally worn or from seizing.
Further, in the conventional scroll compressor, two sealing materials are used to form the frame space 15f. Accordingly, the sealing materials themselves cost, and it is necessary to form two grooves for disposing the sealing materials. Thus, there is a problem that much working time and cost are required.
The present invention has been made in order to solve such problems, and it is another object of the present invention to provide a scroll compressor of the type described which is superior in productivity in that the number of sealing materials themselves and the number of steps for forming the grooves for disposing the sealing materials can be reduced, and that the working for the extraction hole 2j, the communication passageway 3s, and so on, can be eliminated thereby reducing the parts cost and the working cost.
In addition, the conventional scroll compressor uses U-rings made of Teflon or the like as the sealing materials. Accordingly, the material itself is comparatively expensive.
In addition, in the case where the closed vessel is in balanced pressure, as before the compressor starts up, the pressure increases as follows. In the frame space 15f where the refrigerant gas of the intermediate pressure is extracted on the way of compression carried out in the compression chamber 1d immediately after the compressor starts up, the pressure increases comparatively rapidly, while, in the closed vessel, the volume is much larger than the volume of the frame space 15f so that the pressure increases more slowly than the frame space 15f. 
In such a case, for a certain period of time, the pressure levels of the pressure Pm2 of the frame space 15f and the closed vessel pressure (that is, discharge pressure) Pd come into the condition shown by the following expression.
Pm2 greater than Pdxe2x80x83xe2x80x83(15) 
On the assumption of steady-state operation, the sealing materials are formed so as to prevent discharge pressure gas from entering the frame space 15f. However, the sealing materials cannot prevent the flow reverse to that of the discharge pressure gas. In the condition shown by the expression (15), the refrigerant gas in the frame space 15f leaks out into the closed space so that the pressure Pm2 in the frame space does not increase. Thus, the force required to move the compliant frame 3 toward the compression chamber becomes insufficient. In other words, it takes a long time to start a normal compressing operation. In addition, during this period, the compliant frame 3 and the oscillating scroll 2 moving in the axial direction of the compressor in contact with the compliant frame 3 fluctuate in the clearance of the axial relief amount. Thus, there is a problem that damage, seizing, or the like, is caused to the bearings by the occurrence of one-sided bearing of the bearings.
The present invention has been made in order to solve such problems. According to the present invention, O-rings are used instead of Teflon so that the material cost can be reduced.
Even during the starting of the compressor, the pressure Pm2 of the frame space 15f is quickly increased without leaking the refrigerant gas of intermediate pressure supplied from the compression chamber 1d to the frame space 15f. Thus, the force required to move both the compliant frame 3 and the oscillating scroll 2 toward the compression chamber is generated positively so that a normal compressing operation can be started quickly.
It is therefore another object of the present invention to provide a scroll compressor of the type described which is low in cost, superior in starting performance, free from damage of bearings, and high in reliability.
In addition, if conventional O-rings typically made of CR (chloroprene rubber) are used as the sealing materials in the case where an HFC refrigerant (R407C, R410A, etc.) is used as a working fluid, the O-rings are swollen and deteriorated due to compatibility with the refrigerant. Thus, there is a problem that the sealing materials lose their sealing properties.
The present invention has been made in order to solve such a problem. It is therefore another object of present invention to provide a highly reliable scroll compressor of the type described in which O-rings made of HNBR (in which hydrogen atoms are bonded with a part of acrylonitrile-butadiene rubber molecules) are used for the HFC refrigerant so that the O-rings do not deteriorate and do not lose their sealing properties.
According to the present invention, there is provided a scroll compressor disposed in a closed vessel, comprising: a fixed scroll and an oscillating scroll respectively having plate-like scroll teeth in gear with each other so as to form a compression chamber therebetween; a compliant frame for supporting the oscillating scroll in an axial direction of the scroll compressor while supporting a main shaft in a radial direction of the scroll compressor for driving the oscillating scroll, the compliant frame being displaceable in the axial direction; and a guide frame for supporting the compliant frame in the radial direction, the oscillating scroll being made movable in the axial direction due to movement of the compliant frame in the axial direction relative to the guide frame; wherein the oscillating scroll has a thrust surface on a surface opposite to the plate-like scroll teeth; wherein a boss portion outside space formed inside a thrust bearing of the compliant frame slidable in pressure contact with the thrust surface is disposed midway in a differential pressure oil feed passageway for feeding lubricating oil by use of a running high/low pressure difference of the compressor; and wherein on the assumption that pressure Pm1 (MPa) of the boss portion outside space determined by a restrictor and a pressure regulator provided midway in the oil feed passageway is expressed by Pm1=Ps+xcex1 and a differential pressure value at which a difference between the high and low pressures becomes minimum in a running pressure range of the scroll compressor is expressed by min(Pdxe2x88x92Ps), the value a in the above expression is set to fall in a range of:
0 less than xcex1 less than min(Pdxe2x88x92Ps) 
where
Ps is suction pressure (MPa) of the compressor
Pd is discharge pressure (MPa) of the compressor.
Thus, the highly reliable scroll compressor is obtained which ensures a differential pressure for feeding oil to the oscillating bearing and the main bearing in the whole running pressure range of the compressor while preventing the compliant frame and the oscillating scroll from separating from each other.
Further, in a scroll compressor which is provided in a closed vessel and which comprises: a fixed scroll and an oscillating scroll respectively having plate-like scroll teeth in gear with each other so as to form a compression chamber therebetween; a compliant frame for supporting the oscillating scroll in an axial direction of the scroll compressor while supporting a main shaft in a radial direction of the scroll compressor for driving the oscillating scroll, the compliant frame being displaceable in the axial direction; and a guide frame for supporting the compliant frame in the radial direction, the oscillating scroll being made movable in the axial direction due to movement of the compliant frame in the axial direction relative to the guide frame, refrigerant gas on the way of compression is extracted from the compression chamber and introduced into a closed frame space formed by disposing two sealing materials on cylindrical surfaces or flat surfaces formed by the compliant frame and the guide frame, and pressure Pm2 (MPa) in the frame space is set to fall in a range of not less than 1.2 times and not more than 2 times the suction pressure Ps (MPa) of the compressor.
Thus, the highly reliable high-efficiency scroll compressor is obtained which makes the fixed scroll and the oscillating scroll slide in contact with each other by a proper pressing force in the whole running pressure range of the compressor so that the fixed scroll and the oscillating scroll are prevented from separating from each other and any increase in sliding loss or seizing caused by excessive pressing is prevented.
Further, in a scroll compressor which is provided in a closed vessel and which comprises: a fixed scroll and an oscillating scroll respectively having plate-like scroll teeth in gear with each other so as to form a compression chamber therebetween; a compliant frame for supporting the oscillating scroll in an axial direction of the scroll compressor while supporting a main shaft in a radial direction of the scroll compressor for driving the oscillating scroll, the compliant frame being displaceable in the axial direction; and a guide frame for supporting the compliant frame in the radial direction, the oscillating scroll being made movable in the axial direction due to movement of the compliant frame in the axial direction relative to the guide frame, a sealing material for stopping fluid from moving from a high pressure space to a low pressure space is disposed on a cylindrical surface or a flat surface formed by the compliant frame and the guide frame.
Thus, the scroll compressor is obtained in which the number of parts, the working time and the cost are reduced and which is low in cost and high in productivity.
In addition, if each sealing material is formed into an O-ring, the cost of the sealing material can be reduced. Further, even during starting of the compressor, the compliant frame and the oscillating scroll move toward the compression chamber quickly without leaking the pressure of the frame space into the closed vessel. Thus, a normal compressing operation can be started. Accordingly, the scroll compressor is obtained which is low in cost and high in reliability.
In addition, in the case of an HFC refrigerant (R407C, R410A, etc.) used as a working fluid, the sealing material may be made of HNBR (in which hydrogen atoms are bonded with a part of acrylonitrile-butadiene rubber molecules) and formed into an O-ring. As a result, it is possible to obtain sealing properties which ensure the reduced danger of swelling or deteriorating of the O-ring. Thus, the highly reliable scroll compressor is obtained.